Function calls

[Andrei Alexandrescu]

Lutger wrote:
> On 01/28/2010 11:05 PM, Andrei Alexandrescu wrote:
>> Michiel Helvensteijn wrote:
>>> Andrei Alexandrescu wrote:
>>>
>>>>>> foreach (line; stdin.byLine()) { ... }
>>>>>>
>>>>>> vs.
>>>>>>
>>>>>> foreach (line; stdin.byLine) { ... }
>>>>>>
>>>>>> How do I choose?
>>>>> byLine is a property. It is fetching a range on stdin.
>>>>>
>>>>> -Steve
>>>> Damn. I was sure the answer will be different.
>>>
>>> byLine() is a function. It changes the state of stdin. Calling it
>>> consecutively will in general result in different return values. If 
>>> there
>>> were two guys: stdin.currentLine (property) and stdin.nextLine(), it
>>> would
>>> be a different story.
>>>
>>> A property should act very much like a field. The advantages of
>>> properties
>>> are that they can be derived (not have a one-to-one relation with a
>>> storage
>>> location) or can do some clever caching/memoizing/logging.
>>
>> I agree, but I'll also note that I got contradictory opinions from
>> different supporters of @property. So now it looks all the more like a
>> judgment call, which is exactly what I was worried in the first place.
>>
>>> Omitting parentheses on an action just because you can is stupid. It
>>> actually makes the language less readable and less predictable. And all
>>> that for saving two keystrokes.
>>
>> I found my code to be more readable and just as predictable with the
>> current rule. And it's not about two keystrokes, it's about persistent
>> and ubiquitous syntactic noise.
>>
>> Gosh, @property does suck. I was afraid that'd be true.
>>
>>
>> Andrei
> 
> Lot's of things are judgement calls, I don't see the problem. @property 
> is a tool like everything else, there are many more cases where it's 
> pretty clear cut. The ambivalence here is inherent in the code, and only 
> brought out by the @property question, not caused by it. Notice there 
> was also no consensus of what byLine actually did under the hood.
> 
> Also, don't forget these:
> - @property allows you to forbid the caller using parenthesis, there is 
> no other way in D to achieve this for accessor functions
> - so far ignored in this thread: any kind of code inspection 
> (reflection, compile time, by IDE) can use the '@property property' for 
> various purposes.

Wise words. So how do I go about byLine?

Andrei